The present invention relates to vehicle transporters and, more particularly, to a system for supporting and retaining the vehicular cargo of a vehicle transporter.
Vehicles such as automobiles and light trucks are commonly transported on trucks, trailers and railway cars that are specially equipped for supporting and restraining the vehicular cargo. The cargo vehicles are typically supported on their respective running gear on vehicle supports which are, in turn, supported by the frame of the transporter. In over-the-road vehicle transporters, the wheels of the cargo vehicles typically engage elongate, perforated deck plates that are attached to a framework of a vehicle support structure and which extend parallel and adjacent to the sides of the transporter's frame. The vehicle support may be fixed in the frame of the transporter, but is often movable relative to the transporter frame to permit orienting the cargo vehicles so that the payload can be maximized and the height of the transporter reduced to satisfy legal requirements and clear overpasses and other obstacles. The vehicle supports are also commonly movable to form a surface over which the cargo vehicles can be driven during loading and unloading of the transporter. After being driven into position, the cargo vehicle is typically secured to the vehicle support to prevent movement of the vehicle due to the movement of the transporter.
Referring to FIGS. 1A and 1B, cargo vehicles 20 are commonly restrained by attaching four chains 22 to the vehicle's frame or to tie-down eyes near the corners of the vehicle's body; a procedure known as a hard tie-down. One end of the chain 22 is attached to the cargo vehicle and the other end is attached to the transporter's vehicle support 24. To prevent movement of the cargo vehicle, the chains are arranged so that tension exerted by the chains attached to the front of the vehicle acts in a direction opposite to tension exerted by the chains attached to the rear of the vehicle. Manually operated ratcheting and clamping devices are commonly used to tighten the chains and prevent the chains from loosening.
Since vehicles vary in size and construction, the arrangement of the chains is typically different for each cargo vehicle model. As a result, detailed tie-down procedures and frequent training are required to apprise transporter operators of proper tie-down methods. However, even with training hard tie-downs can be difficult to execute. Chain tensioning devices that are separate from the transporter may be attached to different points on the transporter to align the point of attachment of the chain to the vehicle and point of attachment to the transporter. However, loose chains and tensioners are easily misplaced and must frequently be carried up a ladder or up the side of the transporter's frame to reach vehicles of the transporter's upper tier of cargo. To prevent loss and reduce cargo damage or operator injury resulting from handling the heavy chains and tensioners, the chain tensioners 26 are commonly are affixed to the vehicle supports 24 and the chains 22 are commonly attached to the chain tensioners.
While a chain 22 may directly connect the chain tensioner to a tie-down eye proximate one of the outer corners of the vehicle, as illustrated in FIG. 1A, it is often necessary to attach the chain to the vehicle's frame at a point between the vehicles wheels, as illustrated in FIG. 1B. To prevent the deck plate from interfering with the routing of the chain, the chain tensioners are typically affixed to the vehicle supports so that the chain extends from the tensioner on the inside of the inner edge of the deck plate. If the connection to the vehicle is located between the front and rear wheels, the chain 22 is commonly routed around an idler 28 before being attached to the vehicle so that the tension in the chains act in opposing directions. The idler is typically one of several tubes that are spaced along the inner edge of the vehicle support 24 and project toward the center of the transporter. Since the routing of the chain from its connection on the tensioner to its connection to the cargo vehicle is variable, it is difficult for the operator to determine the correct force to apply to the chain tensioner to achieve adequate chain tension. This is particularly true when a chain, which may be corroded from exposure to the environment, must be routed over the edge of the vehicle support or around an idler that is worn or corroded. Since the tension in the chain is variable and unpredictable, the tension in the four chains used to secure a vehicle is frequently not equal and operators commonly over tighten the chains to ensure the security of the cargo vehicle or to pull the vehicle's body down to reduce the overall height of the transporter. This may damage the cargo vehicle or even cause personal injury to the operator when tightening or releasing the chains.
Many newer cars and some other vehicles utilize unitized body construction and do not have separate frames providing convenient points for attaching chains for a hard tie-down. If a convenient tie-down attachment point is not provided on the cargo vehicle's frame or body, a transporter operator may attempt to tie the vehicle down by attaching tie-down chains to the vehicle's suspension which can damage the vehicle. Referring to FIG. 2, an alternative to hard tie-down vehicle retention is a soft tie-down vehicle restraint where the individual wheels 40 of the cargo vehicle are restrained to the vehicle supports 41. After the vehicle is positioned on the vehicle support, a flexible strap 42, part of a strap assembly 60, is laid over the upper portion of the circumferential surface of the vehicle's wheel 40. The strap 42 commonly comprises a synthetic material such as nylon. A first end 44 of the strap 42 is anchored to the deck plate 47 of the vehicle support 24 on one side of the wheel. A hook or a block 46 attached to the first end 44 of the strap 42 is engaged with the deck plate by insertion in one of a plurality of apertures 48 in the deck plate. On the opposite side of the wheel, the strap 42 is routed through an idler 50 that also includes a hook or block 51 for engaging another aperture in the deck plate and the second end of the strap is anchored to the vehicle support 24 by a similar hook 52 that engages yet another aperture in the deck plate 47. The idler 50 is arranged to engage the vehicle support and restrain movement of the strap relative to the vehicle support at a point proximate to the wheel 40. A ratchet 54, incorporated in the strap assembly 60, is manually operated to wind up a portion of the strap, shortening the length of the strap between its first and second ends and tensioning the strap. Rotation and translation of the vehicle's wheel is resisted by the tensile forces exerted by the strap on the vehicle support and the friction between the strap, the vehicle support and the wheel.
While the soft tie-down restraint provides an alternative to a hard tie-down vehicle restraint, particularly for vehicles that do no have separate frames, and reduces damage resulting from inappropriate application of restraining force to vulnerable componentry, the soft tie-down method is not always the better alternative for restraining the vehicular cargo. The tires of the cargo vehicle can be damaged when the soft tie-down restraint is used. As the cargo vehicle shifts against the restraining strap, the strap rubs against the tire and can damage or become embedded in the tread. Relative movement of the strap and the wheel and embedding of the strap in the tread are aggravated, respectively, by under-tensioning or over-tensioning of the strap 42. However, it is difficult to accurately tension the strap with a strap mounted ratchet 54 because the angle at which the operator applies force to the ratchet handle 56 changes as the handle moves and as the operator assumes differing positions relative to the ratchet to secure vehicles at the various positions on the transporter. In addition, the combined ratchet and strap assembly is a loose item that can easily be lost, damaged or dropped on one of the cargo vehicles. Moreover, the perforated deck plates of the typical vehicle support provide a limited number of places for attaching the restraining strap to the vehicle support. On the other hand, the transverse position of the wheel on the vehicle support is highly variable due to differences in vehicle position and tread width. As a result, aligning the strap and the points of engagement of the strap to the transporter with the lateral center of the wheel's surface is a matter of chance. However, if the strap and the attaching points are not centered on the wheel, the strap can work its way off of the wheel as the cargo vehicle shifts against the strap and unanticipated loading can be imposed on the cargo vehicle's steering and suspension components.
While the soft tie-down vehicle restraint provides an alternative to the hard tie-down vehicle restraint that is appropriate, and even necessary, for some vehicles, it is not always the better method of restraint and, due to limitations in the construction of transporters and vehicle retention hardware; it is often difficult to execute either method correctly. What is desired, therefore, is a vehicle transporter having a low tare weight and a large payload that includes a cargo vehicle support system providing convenient and accurate vehicle restraint utilizing either a hard tie-down or a soft tie-down to restrain the vehicular cargo.